CN116194513A

CN116194513A - Wire enamel composition comprising polyamideimide

Info

Publication number: CN116194513A
Application number: CN202180064490.XA
Authority: CN
Inventors: A·切西; G·洛吉; G·比昂迪
Original assignee: Allantas Europe Ltd
Current assignee: Allantas Europe Ltd
Priority date: 2020-09-22
Filing date: 2021-09-20
Publication date: 2023-05-30
Also published as: WO2022063715A1; US20230287180A1; KR20230052939A; EP4217413A1; JP2023542189A

Abstract

The present invention relates to a polyamideimide composition which is very suitable for use as primary insulation for wires. The composition comprises 55 to 65pbw of N-butyl pyrrolidone, 25 to 40pbw of a polyamideimide resin, 0 to 20pbw of other components, wherein the polyamideimide resin has a Mw between 10000 to 40000g/mol (daltons) and a Mw/Mn ratio between 1.1 to 2.

Description

Wire enamel composition comprising polyamideimide

The present invention relates to a wire enamel (wire end) composition comprising a polyamideimide.

In transformers, generators and motors, the electrically insulating material protecting the copper or aluminium wires is a thin coating of high performance polymer. The coating, known as primary electrical insulation or wire enamel, is as thin as possible to obtain the maximum number of turns in each slot space. Sufficient thermal, mechanical and electrical properties must be maintained. One such polymer used as primary electrical insulation is a poly (amide-imide) or polyamideimide resin. Prominent features include high thermal performance, chemical and abrasion resistance, and low coefficient of friction.

The polyamideimide coating compositions form flexible and durable films and are particularly useful as wire enamels, varnishes, adhesives for laminates, non-stick coatings, polyamideimides, and the like. These compositions are known in particular for their long-term high-temperature capability (=220 ℃ (430F)).

In GB570858, it is disclosed to prepare an aromatic polyamideimide resin by reacting trimellitic anhydride and an aromatic diamine. Typically these reactions are carried out in aprotic solvents such as N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) or Dimethylformamide (DMF).

In US3541038, the preparation of aromatic polyamideimide resins using trimellitic anhydride and a polyisocyanate, preferably a diisocyanate, is described. This reaction is preferably carried out using N-methylpyrrolidone (NMP) as solvent. Alternatively, a mixture of NMP and aromatic hydrocarbon may be used as the solvent.

It was discovered in the near past that people exposed to NMP may be potentially health-affected. Alternative solvents, such as Tetrahydrofuran (THF), methyl Ethyl Ketone (MEK), gamma-butyrolactone (GBL) or dimethyl sulfoxide (DMSO), are known, but they have the disadvantage of having a boiling point too low to be used as a reaction solvent, a low solubility of the polymer resin or poor storage stability, which may alter the properties of the polymer in the application in which it is to be used.

Although NMP is safe when operated in the correct way and taking sufficient safety and health precautions, various documents relating to alternative solvents have been disclosed, such as those disclosed in US2013/0217812, WO2013/090933, WO2013/107822, US2015/0299393 and WO 2015/144663.

In US2015/0299393 the preparation of polyamideimide resins in alternative lower toxic solvents such as N-formyl morpholine (NFM) and N-acetyl morpholine (NAM) is disclosed. These less toxic solvents (primary solvents) may be used in combination with a co-solvent (or secondary solvent), wherein the amount of co-solvent is lower than the amount of primary solvent. A number of potential co-solvents are mentioned in this document. The polyamideimide resins prepared in this way are said to be useful as coating compositions for wire coatings, but there are no known commercial wire coating systems based on these compositions.

Various solvents that can be used as replacement solvents to replace NMP in wire enamel compositions comprising polyamideimide resins are disclosed in WO 2013/107822. Examples of wire enamel compositions suitable for enamelling copper wire are given in WO 2013/107822. The inventors of the present application repeated the experiments in WO2013/107822 and found that, although some properties of the enameled copper wire using the alternative solvent were comparable to the results obtained using the NMP solvent, the properties of the enameled copper wire using the alternative solvent were generally insufficient to use the composition as a substitute for the NMP-based composition. In particular, the cut-through resistance, ethanol resistance, flexibility and Tan delta do not meet the commercial specifications of NMP-based polyamideimide resin compositions for wire enamel applications.

The present invention relates to a composition which meets all the requirements for a wire enamel composition which is qualified for the true replacement of a solvent comprising NMP.

The composition according to the invention comprises:

55 to 65pbw of N-N-butylpyrrolidone (NBP)

25 to 40pbw of a polyamideimide resin

0 to 20pbw of other Components

Wherein the polyamideimide resin has a Mw between 10000 and 40000g/mol (daltons) and a Mw/Mn ratio between 1.1 and 2.

The invention further relates to the use of such a composition as an insulating material for copper or aluminum conductive materials.

The invention further relates to the preparation of polyamideimide resins in which N-butylpyrrolidone is used as solvent in the presence of a modifier compound to react an anhydride with a diisocyanate at a temperature of 80 to 120 ℃.

The invention further relates to a method for enamelling metal wires with the composition according to the invention.

The polyamideimide resin used in the present invention may be derived from a polycarboxylic acid or anhydride thereof in which two carboxyl groups are located in ortho positions and in which at least one additional functional group must be present, and from a polyamine having at least one primary amino group capable of forming an imide ring, or from a compound having at least 2 isocyanate groups. The polyamideimide can also be obtained by reacting a polyamide, a polyisocyanate containing at least 2 NCO groups and a cyclic dicarboxylic anhydride containing at least one additional group which can be reacted by condensation or addition.

In addition, it is also possible to prepare polyamideimides from diisocyanates or diamines and dicarboxylic acids, provided that one of the components already contains imide groups. For example, it is particularly possible to first react a tricarboxylic anhydride with a di-primary diamine (diprimary diamine) to give the corresponding diiminocarboxylic acid, which is then reacted with a diisocyanate to form the polyamideimide.

For the preparation of polyamideimides, preference is given to using tricarboxylic acids or their anhydrides in which 2 carboxyl groups are located in the ortho position. Preference is given to the corresponding aromatic tricarboxylic anhydrides, for example trimellitic anhydride, naphthalene tricarboxylic anhydride, biphenyl tricarboxylic anhydride, and also other tricarboxylic acids having 2 benzene rings and 2 ortho-carboxyl groups in the molecule, as examples given in DE-A19 56 512. Very particular preference is given to using trimellitic anhydride. As amine component it is possible to use the di-primary diamine already described in connection with the polyamidocarboxylic acid. In addition, it is also possible to use aromatic diamines containing thiadiazole rings, such as 2, 5-bis (4-aminophenyl) -1,3, 4-thiadiazole, 2, 5-bis (3-aminophenyl) -3, 4-thiadiazole, 2- (4-aminophenyl) -5- (3-aminophenyl) -1,3, 4-thiadiazole, and mixtures of the various isomers.

Suitable diisocyanates for the preparation of the polyamideimide are aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate and trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, ω '-diisocyanato-1, 4-dimethylcyclohexane, cyclohexane 1, 3-diisocyanate, cyclohexane 1, 4-diisocyanate, 1-methylcyclohexane 2, 4-diisocyanate and dicyclohexylmethane 4,4' -diisocyanate; aromatic diisocyanates such as phenylene diisocyanate, toluene diisocyanate, naphthalene diisocyanate and xylylene diisocyanate, and substituted aromatic systems such as diphenyl ether, diphenyl sulfide, diphenyl sulfone and diphenylmethane diisocyanate; aromatic-aliphatic and aromatic-hydrogenated aromatic diisocyanates, such as 4-isocyanatomethylphenyl isocyanate, tetrahydronaphthalene 1, 5-diisocyanate, and hexahydrobenzidine 4,4' -diisocyanate, are mixed. Preference is given to using 4,4' -diphenylmethane diisocyanate, 2, 4-and 2, 6-toluene diisocyanate and hexamethylene diisocyanate.

It was found that a polyamideimide resin dissolved in NBP which exhibits the necessary beneficial properties for qualifying as wire enamel can only be obtained when the polyamideimide resin is prepared in NBP under well defined reaction conditions. It was found that the reaction temperature should not be too high, preferably in the range of 80 to 130 ℃, more preferably in the range of 80 to 120 ℃. It was found that when the reaction temperature is above 130 ℃, the reaction is too fast and uncontrolled to obtain a polyamideimide resin having a Mw of at least 10000g/mol and a Mw/Mn ratio between 1.1 and 2. When the reaction temperature is lower than 80 ℃, the reaction is so slow (if any) that it cannot be used in practice for producing a polyamideimide resin.

It has further been found to be beneficial to have small amounts of a modifier compound, such as a low molecular weight monoanhydride or monocarboxylic acid, present in the reaction mixture. Examples of suitable low molecular weight monocarboxylic acids include (C1-C10) monocarboxylic acids or C4-C6 branched monocarboxylic acids such as formic acid, acetic acid, propionic acid, etc., examples of suitable anhydrides include phthalic anhydride. The amount of low molecular weight monoanhydride or monocarboxylic acid in the reaction mixture should be 4 to 8 mole% based on the amount of polyamideimide resin formed in the reaction.

The present invention enables the preparation of solutions comprising N-butylpyrrolidone as main solvent and a polyamide imide resin in an amount >21 wt%, said polyamide imide resin having a Mw between 10000 and 40000g/mol (daltons) and a Mw/Mn ratio between 1.1 and 2.

Such a solution may contain other solvents, but the amount of these other solvents is much lower than the amount of N-butylpyrrolidone.

The invention also relates to the manufacture of enamelled wires by using the composition of the invention.

The application and curing of the composition according to the invention does not require any particular or special procedure and conventional application methods can be used. The wire typically has a diameter of 0.005 to 6 mm. Suitable wires include conventional metal wires, preferably copper, aluminum or alloys thereof. The wire shape is not limited, and a circular or rectangular wire may be particularly used. The compositions of the present invention may be applied as a single layer coating, a double layer coating, or a multi-layer coating.

The composition may be applied in conventional layer thicknesses, with dry layer thicknesses being in accordance with standardized values for thin and thick lines. The composition of the invention is applied to a wire and cured in a horizontal or vertical oven. The wire may be coated and cured one to several times in succession. As curing temperature, suitable ranges may vary from 300 to 800 ℃ depending on the conventional parameters for the lacquer and the properties of the wire to be coated. The conditions of the coating, such as number of passes, coating speed, furnace temperature, depend on the nature of the wire to be coated.

In order to enhance the cut-through resistance (cut through resistance) of wires coated with the composition according to the invention, nanoparticles may also be included in the composition according to the invention.

Nanoparticles which can be used in the composition according to the invention are particles whose average radius is in the range from 1 to 300nm, preferably in the range from 2 to 100nm, particularly preferably in the range from 5 to 65 nm. Examples of preferred nanoparticles are nano-oxides, nano-metal oxides, colloidal metal oxides, metal oxides or hydrated oxides of aluminium, tin, boron, germanium, gallium, lead, transition metals and lanthanides and actinides, in particular of the series comprising aluminium, silicon, titanium, zinc, yttrium, vanadium, zirconium and/or nickel, preferably aluminium, silicon, titanium and/or zirconium, which are in the nano-scale in the dispersed phase, can be used alone or in combination. Among the nano metal oxides, nano alumina is most preferable. Examples of nano-alumina are: BYK-LP X20693 of BYK-Chemie GmbH and Nycol AI20OSD of NanoBYK 3610, nycol Nano Technologies lnc, dispel X-25SR and SRL of Sasol Germany GmbH, disperal P2, P3, OS1 and OS2. Among nano-aluminas, ceramic particles of alumina pre-dispersed in a polar solvent, such as BYK-LP X20693 and nanoBYK 3610 of BYK-Chemie GmbH, are preferred.

Nanoparticles may be used with coupling agents. As coupling agent, any well known functional alkoxysilane or aryloxysilane may be used. Of the functional silanes, (isocyanatoalkyl) -trialkoxysilane, (aminoalkyl) -trialkoxysilane, (trialkoxysilyl) -alkyl anhydride, and oligomeric diaminosilane systems are preferred. The alkyl and alkoxy groups of the functional silane have from 1 to 6 carbon atoms, more preferably from 1 to 4 carbon atoms. The above alkyl group and alkoxy group may further have a substituent thereon. Titanates and/or zirconates may also be used as coupling agents. Any of the usual orthotitanates or zirconates may be used, for example tetraisopropyl, tetrabutyl, acetylacetone, acetoacetates, diethanolamine, triethanolamine, cresols titanate or zirconate.

To enhance the dispersion of the nanoparticles in the polymer solution matrix, a coupling agent such as a functional silane, titanate or zirconate may be added directly to the nanoparticle dispersion and mixed therein before loading it into the polymer resin solution or may be added directly to the polymer solution prior to addition of the nanoparticle dispersion. The coupling agent may optionally be mixed into the polymer solution prior to loading the nanoparticle dispersion to better link the inorganic moiety to the organic moiety. The mixture of polymer solution and coupling agent may be stirred at room temperature or at a relatively low temperature for several hours before adding the nano metal oxide solution.

Enamelled wires made according to IEC 60851 test.

Measurement method

Mw is measured in accordance with DIN 55672-2;

mn is measured in accordance with DIN 55672-2;

viscosity was measured according to ASTM D3288;

spindle test (mandril test) was measured according to IEC 60851-part 3.

Ethanol resistance was measured according to IEC 60851-part 4.

The cut-through test was measured according to IEC 60851-part 6.

Tan delta was measured according to IEC 60851-part 5.

The jerk test (jerk test) was measured according to IEC 60851-part 3.

Examples

Example 1 (comparative): experiment 1 from WO2013/107822 was repeated under exactly the same conditions to prepare a solution of polyamideimide in N-butylpyrrolidone (NBP). A polyamideimide solution having an average molecular weight of 7136 g/mol was obtained (sample 1).

Example 2: 18.08 parts by weight (pbw) of trimellitic anhydride, 23.5pbw of 4,4' -diphenylmethane diisocyanate, 0.12pbw of formic acid and 58.29pbw of NBP were loaded in a reaction vessel and heated to 85 ℃. The mixture was kept at 85 ℃ for 2 hours and then slowly heated to 100 ℃. The temperature in the reaction vessel was maintained at this temperature for several hours.

1 hour after reaching 100℃a sample of 10.9pbw was extracted from the reaction vessel and measured for molecular weight 9665 g/mol (sample 2).

The reaction was continued and after an additional 1 hour a further 10.9pbw of sample was taken from the reaction vessel and the molecular weight was measured to be 15593 g/mol (sample 3).

The reaction was continued and after an additional 1 hour a further 10.9pbw of sample was taken from the reaction vessel and the molecular weight was measured to be 16771 g/mol (sample 4).

The reaction was continued and after a total reaction time of 7 hours at 100℃a further sample of 10.9pbw was taken from the reaction vessel and the molecular weight was measured to be 24583 g/mol. This sample was further diluted with benzyl alcohol to reach a viscosity of 13000mPas at 23 ℃ (sample 5).

Example 3: a typical wire enamel test was performed on all samples collected in examples 1 and 2. In this comparison, a commercially available polyamideimide resin solution in NMP (sample 6) was also used. The results of these experiments are shown in table 1.

Table 1: test results

Sample of

R: requirements for commercial use

* ) Comparative example

Claims

1. A composition comprising

55 to 65pbw of N-N-butylpyrrolidone,

25 to 40pbw of a polyamideimide resin,

0 to 20pbw of other components,

characterized in that the polyamideimide resin has a Mw between 10000 and 40000g/mol (daltons) and a Mw/Mn ratio between 1.1 and 2.

2. The composition of claim 1, further comprising nanoparticles having an average diameter in the range of 1 to 300 nm.

3. The composition of claim 1, obtainable by reacting a mixture comprising a tricarboxylic acid having 2 ortho-carboxyl groups or an anhydride thereof, a diisocyanate, a regulator compound and N-butylpyrrolidone at a temperature of 80-120 ℃.

4. A process for the preparation of a polyamideimide resin, wherein a mixture comprising a tricarboxylic acid having 2 ortho-carboxyl groups or an anhydride thereof, a diisocyanate, a regulator compound and N-butylpyrrolidone is reacted at a temperature of 80-120 ℃ until a polyamideimide resin is obtained having a Mw in the range of 10000 to 40000g/mol (daltons) and a Mw/Mn ratio of between 1.1 and 2.

5. The method according to claim 4, wherein the modifier is a low molecular weight monocarboxylic acid.

6. The process according to claim 5, wherein the low molecular weight monocarboxylic acid is selected from the group consisting of formic acid, acetic acid and propionic acid.

7. The method according to any one of claims 4-6, wherein the mixture further comprises nanoparticles having an average diameter in the range of 1 to 300 nm.

8. A method of coating a metal wire, wherein the wire is coated with the composition of claims 1-3.